Here me out.
The cars are in the used lot appear for a reason.
There are the
Event Cars- Cars that you see after completing an event
Rare- Cars that have a low chance of popping up
Normal- Cars that you often see.
Sometimes event cars turn into normal cars. Anybody else think this?
I have come to the conclusion that there is not a outright pattern. Unless this game is using a complex math algorithm. I have seen times when a car (S4) is in my car lot 3 times at the same time. Same color with miles/KM that are separated by 10 and price difference of 100 credits.